1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method thereof.
2. Description of Related Art
The semiconductor device disclosed in Patent Document 1 includes a schottky barrier diode connected between the source and the drain. More specifically, in the semiconductor device, a p-type base layer is formed in the surface portion of an n-type semiconductor layer formed on an n-type semiconductor substrate. A trench is formed from the surface of the n-type semiconductor layer so as to penetrate the p-type base layer, and on the side walls and the bottom of the trench, a gate insulating film is formed. A gate electrode is embedded in the trench. An n-type diffusion layer is formed in a surface portion of the p-type base layer.
With this configuration, this semiconductor device is equipped with a trench gate type transistor. In this transistor, the n-type diffusion layer is a source region, the n-type semiconductor layer is a drain region, and a channel is formed near the boundary between the gate insulating film and the p-type base layer formed between the n-type diffusion layer and the n-type semiconductor layer. As a result, an electric current flows between the source region and the drain region.
A metal layer is deposited on the surface of the n-type semiconductor layer. The metal layer is in contact with the n-type diffusion layer, thereby functioning as a source electrode, and also, by the metal layer being in contact with the surface of the n-type semiconductor layer in a region where the p-type base layer is not formed, a schottky junction is formed between the region and the metal layer. As described above, in this semiconductor device, a transistor and a schottky barrier diode are formed in one chip.